George Clooney – as director and co-writer – has produced yet another intelligent film, a dark political drama with a great cast working at the top of their games.

Based on Beau Wilimon's stage play Farragut North this is the story of a Democratic primary in which fratricidal conflict exposes the base ambitions and personality weaknesses behind the idealistic language.

Darker and more cynical than The West Wing, in which Martin Sheen was the last great hope of American liberalism, Clooney in the role of Governor Mike Morris is perhaps more real. The central dilemmas are whether liberals can be good human beings and great politicians - and what do we do when our idols let us down. These are embodied in Ryan Gosling's role as the idealistic press aide Stephen Meyers. His political skills make him attractive to Evan Rachel Wood's intern and Clooney's opponent, represented by Paul Giamatti; both play on his pride and his anger at his own candidate's flaws.

Clooney has often spoken of his admiration for the political thrillers of the 1970s and this film brings to mind Robert Redford in Michael Ritchie's 'The Candidate' and the work of director Alan J Pakula, but perhaps in this century we have come to realise that we will inevitably be betrayed by our political idols, our demands on them are too high. The unstated question in 'The Ides of March' is should the left seek a good man like Barack Obama, who is proving an ineffective politician or a morally flawed man like Bill Clinton who was a political pro? Clooney has used his own celebrity clout to support his political views, but as with Warren Beatty he has realised that a man with a private life cannot succeed on the American political stage. Indeed he has more power as a celebrity in the Senate hearings on the Darfur massacres than he would in electoral politics.

'The Ides of March' sometimes betrays its theatrical origins and the roles of Evan Rachel Wood and Marisa Tomei are somewhat clichéd. But as with the superior 'Good Night and Good Luck' Clooney has used his star power, intelligence and liberal credentials to attract a superior cast of Hollywood's best. The work of these actors led by Ryan Gosling show that a great cast can elevate a script to a truly worthwhile film for grown-ups.